The difference in PFS between the IVO arm, 85%, versus 87% in the IO arm was statistically insignificant.
“Due to the early read-out and the futility boundaries being crossed, long-term follow-up will be critical to understand if there are any long-term benefits to IVO,” said study principal investigator Jennifer A. Woyach MD, professor in the division of hematology at The Ohio State University Comprehensive Care Center (OSUCCC – The James) in Columbus.
The Ohio State University Comprehensive Care Center
Dr. Jennifer A. Woyach
The 14-month follow-up data includes results from 465 CLL patients aged 65+ (median age 74 years, 67.5% male) who were treatment naive. The IO and IVO arms had 232 and 233 participants respectively, patients across both arms had Eastern Cooperative Oncology Group scores of 0-1 (97%), occurrence of Del (17p) was 13%, and a Rai stage status of III/IV was 55%, slightly more patients in the IO arm had unmutated IGHV 55% vs. 47% in the IVO arm. Researchers noted that, as expected, patients in the IVO group had a greater occurrence of hematologic adverse events graded at 3 or above, 61% VS 48% in the IO arm, P =.006.
The trial was spurred by the fact that many CLL patients on IO therapy must remain on treatment indefinitely, and an earlier phase II trial suggested that IVO therapy could lead to deep remission and therapy discontinuation.
Looking at the complete response (CR) rates and undetectable minimal residual disease (uMRD) rates across both arms suggested that there may be some hope that IVO could help CLL patients achieve deep remissions and discontinue therapy. Patients in the IVO arm had a CR of 68.5% and uMRD of 86.8% while only 31.3% of those in the IO arm had a CR and 33.3% achieved uMRD status.
“Despite the impressive CR and uMRD results, this study demonstrates that IVO is not superior to IO in terms of progression-free survival. However, because many patients in the IVO arm have discontinued treatment while those in the IO arm remain on ibrutinib, we think that it will be very important to continue to follow these patients long term, to see if there are advantages to this time limited therapy, especially in terms of toxicity, that we cannot appreciate with this follow-up,” said Dr. Woyach.
The Alliance for Clinical Trials in Oncology cooperative group, including OSUCCC James, is currently working to design the next frontline CLL study for older patients that builds on this work.
Dr. Woyach disclosed ties with Abbvie, AstraZeneca, Beigene, Genentech, Janssen, Loxo/Lilly, Merck, Newave, Pharmacyclics, and Schrodinger.